At least 14 people have died in a series of clashes between gunmen and federal police in Mexico, just as the government announced a 14% drop in drug-related killings.

The deaths took place in Michoacan state, a western area that has seen a surge of violence in recent years attributed to drug cartels.

Federal police said in a statement the first gun battle began when officers aboard a helicopter spotted armed men traveling in four vehicles in the town of Gabriel Zamora. The gunmen opened fire on the agents, who shot back and killed five assailants, the statement said.

It said one of those killed was high in the leadership structure of a Michoacan-based drug cartel but did not identify the group.

Hours later in the town of Apatzingan federal agents were accompanying a caravan of citizens commemorating the anniversary of the death of the Mexican revolutionary Emiliano Zapata when gunmen fired shots at some of the participants. Police killed one of the gunmen, authorities said.

The citizens continued on and were again attacked by gunmen who fired from an overpass, police said. Eight people died and another eight were wounded, including two police officers.

The Knights Templar cartel, which controls much of Michoacan, has been fighting rivals along its borders with other states including Guerrero, where a variety of smaller cartels control drug smuggling and other criminal activities.

On Wednesday when the clashes took place the Mexican government announced drug-related killings from December through March had dropped 14% from the same period a year earlier. The interior department said 4,249 people were killed during the first four months of President Enrique Peña Nieto's administration. It said 4,934 were killed between December 2011 and March 2012.

But interior secretary Miguel Angel Osorio Chong said it was "too early to assume victorious attitudes".

The government of previous President Felipe Calderón stopped releasing figures of drug killings in September 2011, but Osorio Chong said the federal government had continued to keep a count.

The interior department report said 184 law enforcement officials were killed between December and March, including soldiers, and federal and local police.

Bloody clashes are still common in Mexico and it can be impossible to know how many people died because drug traffickers take their dead away before authorities reach the scene.

In the border city of Reynosa there were at least four major shootouts between rival drug gangs in March. One of the clashes lasted several hours. People reported dozens of dead on social networks and at least 12 were corroborated by witnesses. The official account only listed two dead.

Osorio Chong said the state of Tamaulipas, where Reynosa is located, is one of the "most important spots for this administration" when it comes to security.